Aspirin Overview
What aspirin is, why it is studied in oncology, and where the evidence is strongest
Aspirin is a long-established non-steroidal anti-inflammatory drug. It is best known for pain relief, fever reduction, and cardiovascular prevention.
In oncology, it is drawing serious repurposing interest because it affects inflammation, platelet biology, immune surveillance, and tumour signalling at the same time. The strongest current human signal is in PIK3CA-mutated colorectal cancer, where aspirin now has Phase 3 support.
At a Glance
What it is: An oral NSAID that irreversibly inhibits COX-1 and COX-2
Why it matters: It may reduce tumour-promoting inflammation, metastatic spread, and recurrence risk
Best-supported use today: Investigational adjuvant use in PIK3CA-mutated colorectal cancer
Strongest evidence: Phase 3 trial data in biomarker-selected colorectal cancer
Main limitation: Bleeding risk and uneven benefit across populations
Why aspirin is studied in oncology
Aspirin sits at the intersection of inflammation, immunity, and metastasis.
Research suggests it may:
suppress COX-driven tumour inflammation
reduce platelet support for metastatic spread
enhance anti-tumour immune activity
affect p53, DNA repair, and cell-cycle control
modulate Wnt / β-catenin and related survival pathways
Clinical Positioning
Current evidence best supports aspirin as an investigational repurposed adjunct, not as a replacement for standard cancer therapy.
Its strongest current relevance is in the overlap between:
biomarker-selected colorectal cancer
inflammation-linked tumour biology
anti-metastatic strategy
low-cost repurposed-drug interest
Evidence Quality Rating
3.5/5 — Moderate evidence overall, with stronger support in selected colorectal-cancer subgroups
This rating reflects a large prevention and mechanistic literature, plus important prospective trial data in biomarker-selected colorectal cancer, but limited definitive oncology use across other tumour types.
Where to Go Next
Key References
Elwood P et al. (2021). Aspirin and cancer survival: a systematic review and meta-analyses of 118 observational studies (~20% reduction in cancer mortality across 18 cancer types). ecancer 15:1258. https://doi.org/10.3332/ecancer.2021.1258[^1][^2]
Cuzick J et al. (2024). Aspirin and cancer treatment: systematic reviews and meta-analyses of evidence for and against. British Journal of Cancer 130:1–15. https://doi.org/10.1038/s41416-023-02506-5[^3][^4]
Li Y et al. (2025). Effect of aspirin use on cancer incidence and mortality: a meta-analysis. Public Health 248:105924. https://pubmed.ncbi.nlm.nih.gov/40865396/[^5]
Li K et al. (2025). Long-term use of low-dose aspirin for cancer prevention (population study: 538,147 aspirin users, SHR 0.92 for cancer risk; SHR 0.80 for cancer mortality). Cancer Medicine 14(1). https://pmc.ncbi.nlm.nih.gov/articles/PMC12008822/[^6]
Drew DA et al. (2021). Evaluation of Aspirin Use With Cancer Incidence and Survival (PLCO trial cohort, 139,896 participants). JAMA Network Open 4(1):e2033622. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2775219[^7]
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This information is for education only. It is not medical advice, diagnosis, or treatment. Please speak with a qualified clinician before making changes to care, medication, or supplement use.
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